NG-98-2059, Provides Response to NRC Request for Background Summary of TS Change (TSCR-006), Revise TS 3.6.1.3 Condition E & Add TS for Control Bldg/Standby Gas Treatment (Cb/Sbgt) Instrument Air Sys

Provides Response to NRC Request for Background Summary of TS Change (TSCR-006), Revise TS 3.6.1.3 Condition E & Add TS for Control Bldg/Standby Gas Treatment (Cb/Sbgt) Instrument Air Sys

ML20198K651
Person / Time
Site:	Duane Arnold
Issue date:	12/21/1998
From:	Peveler K IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NG-98-2059, NUDOCS 9812310120
Download: ML20198K651 (5)

Text

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l H A L I;I A N T

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lES Utilities 3277 DAEC Road l'alo,IA 52324P785

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. December 21,1998 ** =:lianta"n ==

. NG-98-2059

. Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station PI-37

- Washington, DC 20555-0001 '

t E

Subject:

Duane Arnold Energy Center Docket No: 50-331 Op. License No: . DPR-49 Responsp to NRC Request for Background Summary of Technical Specification Change (TSCR-006): " Revise TS 3.6.1.3 Condition E and Add a Technical Specification for the Control Building / Standby Gas Treatment (CB/SBGT) Instrument Air System"

Reference:

1) NG-98-1764 dated October 15,1998; Request for Technical Specification Change (TSCR-006): " Revise TS 3.6.1.3 Condition E and Add a Technical Specification for the Control Building / Standby Gas Treatment (CB/SBGT) Instrument Air System" l l

File: A-117

/

)

Dear Sir (s):

Upon receipt of Reference 1, NRC Staff verbally requested some background summary 4 00 information to help facilitate their review. Attachment I to this letter provides the requested information.

The Reference I submittal (10 CFR 50.92 Evaluation, Proposed Change, Safety Assessment, and Environmental Consideration) is not affected by the information provided in Attachment I to this letter. I No new commitments are made by this letter.

9812310120 981221F POR ADOCK 0S000331 P PDR_

NG-98-2059 December 21,1998

. Page 2

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Should you 4.ve any questions regarding this matter, please contact this office.

Sincerely,'

Kenneth E. Peveler

- Manager, Regulatory Performance '

l Attachments: 1) TSCR-006; IES Response to NRC Verbal Request '

cc: A. Roderick i E. Protsch J. Franz '

D. Wilson -

R. Laufer (NRC-NRR)

J. Caldwell(Region 111)

P. Baig (State ofIowa)

NRC Resident Office Docu a.

., i .

TSCR-006 Attachment 1 to IES Response to NRC Verbal Request NG-98-2059 Page1of3 NRC reauest Please identify the specific systems / components supported by the CB/SBGT Instrument Air System, the applicable Tech Spec Conditions and associated Completion Times.

IES Utilities Inc. response i

The following table identifies the specific systems / components' that require compressed air to perform their safety function, and the applicable Tech Spec Condition (with associated Completion Time) that would currently exist under the definition of OPERABILITY when a CB/SBGT Instrument Air subsystem is unavailable:

CB/SBGTInstrument Air Applicable Tech Spee Subsystem A Subsystem B Comments 3.6.1.3 PCIVs CV5704A CV5704B Compressed air is required for closure of CV5718A CV5718B the Well Water isolation valves.

Condition C 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 3.6.1.3 PCIVs CV4301 CV4300 Compressed air is required to ensure leak CV4302 CV4303 tightness of the containment purge valves Condition E CV4306 CV4307 that have T-ring seals.

, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> CV4308 3.6.1.6 RB-Torus CV4304 Coinpressed air is required for closure of Vacuum Breakers CV4305 the butterfly valves and to ensure leak tightness of the butterfly valves that have Condition A T-ring seals.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 3.6.4.3 SBGT System E/PC5816A E/PC5816B Compressed air is required for regulating DO5816A DO5816B the train flow rate and for opening the Condition A AV5801A AV5801B cool down air flow damper, 7 days 3.7.4 SFU System E/PC7320A E/PC73208 Compressed air is required for regulating AV7318A AV7318B the train flow rate and to provide a Condition A ventilation flow path via the Control 7 days Building Chiller (CBC) System. (

3.7.5 CBC System DO6112A DO6112B Compressed air is required for opening DO6113A DO6113B dampers to establish a ventilation flow Condition A DO6127A DO6127B path and for regulating valves to provide 30 days TC6116A TC6116B temperature control.

CV6115A CV6115B CV6116A CV6116B

' For the components in this table: M or CVis a pneumatically operated valve; DO is a damper operator; F#C is an electro-pneumatic controller; 7C is a temperature controller

TSCR-006 Attachment I to 1ES Response to NRC Verbal Request NG 98-2059 Page 2 of 3

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t NRC reauest I

l~ i How does the CB/SBGT Instrument Air System satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii)? ,

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IES Utilities Inc. response I

L The CB/SBGT Instrument Air System supports the operability of several systems and components that mitigate the consequences of design basis accidents. While the CB/SBGT Instrument Air System is not a direct mitigation system, the i supported systems and components are part of the primary success path. This is j the same basis used to demonstrate that the Emergency Service Water System and the Diesel Generators satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

NRC reauest What is the basis for effectively extending the Completion Time for an inoperable CB/SBGT Instrument Air subsystem from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 7 days?

IES Utilities Inc. respan The CB/SBG1 instrument Air System is normally supplied _ by the non-safety related main plant instrument air system and the safety-related CB/SBGT Instrument Air compressors are in standby. During loss of offsite power (LOOP) loss of coolant accident (LOCA) conditions, the non-safety related main plant instrument air system loses power, resulting in decreasing pressure in the system.

Each CB/SBGT Instrument Air compressor will start automatically in response to decreasing pressure in the associated air receiver and check valves close to provide isolation of the CB/SBGT Instrument Air subsystem from the main plant instrument air system. The CB/SBGT Instrument Air compressors are powered by the Diesel Generators (DGs) and cooled by the Emergency Service Water (ESW) System during LOOP LOCA conditions. The DGs and ESW System also support other safety related functions, such as ECCS. Thus, the systems / components affected when a CB/SBGT Instrument Air subsystem is inoperable is a subset of the systems / components affected when either a DG or an ESW subsystem is inoperable. Therefore, the 7 day Completion Time for an inoperable CB/SBGT Instrument Air subsystem is justified by comparison to the 7 day Completion Time allowed for either an inoperable DG or an inoperable ESW subsystem I

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.* . TSCR-006

! :.. Attachment I to

IES Response to NRC Verbal Request NG-98-2059 Page 3 of 3 i . r

. .~ 1 l NRC reauest l

Should this be a generic change to the Improved Technical Specifications?

JES Utilities Inc. response The need for safety-related pneumatics, including the specific design features, is very plant specific. Therefore, the change being requested for the DAEC TS was judged to not be generic.

Additionally, this change was reviewed at the most recent BWROG Tech Spec

. Issues Coordination committee meeting (Nov 98). The committee agreed that this is a plant-specific issue and no TSTF traveler was warranted. i NRC reauest Has c. PRA evaluation of the CB/SBGT Instrument Air System (e.g., one subsyem out of service) been performed?

I IES Utilities Inc. response A PRA evaluation of the CB/SBGT Instrument Air System was not performed as part of this Technical Specification Change Request submittal. Such a study is not possible with the present DAEC PRA model because it does not contain a detailed fault tree model of the CB/SBGT Instrument Air Eystem components, i i

However, loss ofinstrument air (i.e., all compressed air sources) is modeled as an I event tree initiator in the DAEC PRA. The Core Damage Frequency (CDF) contribution due to these event sequences is less than 4x10'8 p compared to the total Rev. 4 Intemal Ewnts CDFper of year, 1.11x10',er it is year. When evident thm less than 0.5% of the total CDF for the DAEC PRA is due to failures of the instrument air function. Therefore, the instrument air function is not risk- -!

significant, as measured by CDF contribution. A similar trend in the Level 2 I calculations of Large Early Release Frequency (LERF) also indicates that the  ;

importance of the instrument air function is low.

Based on the above information, the importance of the instrument air function (which includes the CB/SBGT Instrument Air System) is estimated to be low, in 1 particular when compared to other support system trains with similar L.CO L requirements, such as Emergency Service Water and Diesel Generators.

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